Dean Oswald, former Illinois Extension adviser and now a Forage/Grazing Specialist with Midwest Grass & Forage shared the following timely link to a 2005 Iowa State article on frost and alfalfa. The article, authored by Dr. Steve Barnhart stated that alfalfa that has been subjected to a light frost (27° to 31° F) has varying effects on the alfalfa plant. From the article; "Leaves on new alfalfa shoots will often be killed at tissue temperature of about 27° to 28° F (or colder). Buds and growing points are somewhat better insulated at 27° to 28° F and will often continue to grow normally. The only evidence of a light frost will be the loss of several sets of trifoliate leaves down the stem that correlates with the chronological time of the frost. Most plants in the field of a low-lying area will exhibit the same general leaf loss pattern. At these light frosts, the top few inches of alfalfa stems may curl--similar in appearance to 2,4-D herbicide epinasty. Alfalfa plants outgrow this."

Dr. Barnhart further shared that morphological plant development should not be affected by a light frost, and there is no need to change harvest management plans.